As interconnections become multilayered upon the manufacture of a semiconductor device, features with high aspect ratios, e.g., vias or trenches, are formed on a substrate. The features are charged by electroplating a composition. At this time, to minimize defects such as voids and seams, additives such as accelerators, suppressors, or leveling agents may be included in the electroplating composition.
During the process of electroplating using an electroplating composition containing accelerator, bumps are formed due to the presence of the accelerator. As the plating process proceeds, an aggregation of bumps is formed as the bumps grow. At such a time, due to the accelerated formation of the bumps on regions with high aspect ratios and high density, like the features, a bigger aggregation is formed. Such a phenomenon is called overplating. The areas where overplating has occurred form steps from the surrounding regions, and the formed steps cause defects in semiconductor devices due to increase of the processing time during the chemical mechanical polishing process and impedance of surface smoothness.
Accordingly, a leveling agent is added to increase the smoothness of the surface. Conventionally, the use of polyethyleneimine, polyglycine, polyurea, polyacrylamide, polyaminoamide, polyalkanolamine, and so forth as leveling agents has been disclosed. In addition, the use of copolymers of polyvinylpyridine, polyvinylpyrrolidone, vinylimidazole, vinylpyrrolidone, and so on as leveling agents has also been disclosed.
However, such leveling agents still have limits to increase surface smoothness. Accordingly, there is a demand for copper electroplating additives, and which can further improve the smoothness of plated surfaces.
Patent Literature: KR 2004-0045328